Isolated Yeast (Tree House): How to Identify and Characterize?

[lilbova3]

I recently received some brews as well from TH. Got Jjjjuliussss, Juice Project Citra and Nelson, Green and One. It’s been so long since I’ve had TH, I remember the very first time having Julius and Green back in the day and was blown away. Probably because the beer was something I’ve never seen or tasted before. Now, there are so many other great breweries producing these IPAs. I get a lot of peach from their beers and many of them taste the same to me. When I crack one of their beers I don’t get the in your face hops smell that fills the room like some other beers do. However, I do appreciate the color, the mouthfeel, the assertive bitterness (which I feel isn’t from hop burn or over dry hopping). It’s hard for me to pick out the different hops used because I feel it’s muddled by yeast.

I will say, their Bright beers are a wonderful showcase of hops. It’s been awhile and I haven’t done my research but I think they use American Ale yeast with these. You get great pungent hops aroma and flavor.

 

[TBryerton]

I recently received some brews as well from TH. Got Jjjjuliussss, Juice Project Citra and Nelson, Green and One. It’s been so long since I’ve had TH, I remember the very first time having Julius and Green back in the day and was blown away. Probably because the beer was something I’ve never seen or tasted before. Now, there are so many other great breweries producing these IPAs. I get a lot of peach from their beers and many of them taste the same to me. When I crack one of their beers I don’t get the in your face hops smell that fills the room like some other beers do. However, I do appreciate the color, the mouthfeel, the assertive bitterness (which I feel isn’t from hop burn or over dry hopping). It’s hard for me to pick out the different hops used because I feel it’s muddled by yeast.

I will say, their Bright beers are a wonderful showcase of hops. It’s been awhile and I haven’t done my research but I think they use American Ale yeast with these. You get great pungent hops aroma and flavor.

I actually feel the opposite in regards to the market. I think it’s flooded with IPA’s that aren’t very good. Breweries are jumping on this style and pushing out poor beer because they know anything labeled hazy will sell. The last haul I got from TH was a level higher than anything else I’ve had in a long time. The only beer I wasn’t impressed with was Hello Mass. and Hello Cape Cod fell off extremely fast, but was amazing first the first two weeks.

I had to run up to Vermont a couple weeks ago but didn’t have time to make a lot of stops. Hill Farmstead is a great example of what an IPA should taste like. Super clean w/a ton of hop expression. I was also super impressed with River Roost. They stole the show that weekend.

 

[Chris-18]

Been reading this thread ever since it came out, and it's really interesting. This theard made a bit of a stir in the industry when it started, at least for us interesseret in microbiology.

I am a professional brewer in Copenhagen, I used to work for a small craft brewery that is now a very large craft brewery. I just quit there to start my own brewery. And in that regard, I worked at a brewpub and we were producing some of the best rated IPA's in the country. For years we used S-04 as our house strain for almost everything. And we always had this somewhat hot and boozy alcohol flavor and S-04 really mutes hop aroma rather than accentuating it. We tried every permutation of recipes and mashing and fermentation techniques over the years, and never really got it to work - at least in the way we wanted. I recognize S-04 quite easily now, and that is why I'm quite confident in saying that I doubt that Tree House is using S-04 as their base yeast. Having had a few of their beers, I didn't recognize the flavor as S-04 at all. However I'm also sure it's not something like London Ale III, but it's not far off.
We ended up having to assault the beers with dry-hopping to overcome this muting effect and it never really went our way. Only when we switched to LAIII derivatives and other English strains did we get more hop aroma and flavor.

Just thinking of the logistics, if Tree House was using a dry yeast blend, then they have to pitch fresh yeast every time, otherwise their blend would get out of balance after the first fermentation. That means maybe 5-10 kg of dry yeast pr. Tank (I forget their biggest tank size but I believe the GEA brewhouse is around 80 hL). That's a massive cost, something I really can't see them doing for every brand. Them doing it every now and then is possible, but for every IPA they make or even the majority? No way. The cost of yeast pr batch would be enormous.

However, it seems like that from other threads and articles that they do indeed use a mixed yeast culture for Julius, which seems reasonable, as it started life as a homebrew recipe from what I know.

Just throwing another thought out there; I know of at least 2 breweries that intentionally add different yeasts post fermentation, in order to screw up the blend so that people can't easily culture up their dregs and to keep their real yeast "secret". I'm not saying TH are doing that, it's just worth mentioning that it happens. Contamination in the brewery is also possible.

Anyway, just throwing some professional S-04 experience out there.

 

[TBryerton]

Been reading this thread ever since it came out, and it's really interesting. This theard made a bit of a stir in the industry when it started, at least for us interesseret in microbiology.

I am a professional brewer in Copenhagen, I used to work for a small craft brewery that is now a very large craft brewery. I just quit there to start my own brewery. And in that regard, I worked at a brewpub and we were producing some of the best rated IPA's in the country. For years we used S-04 as our house strain for almost everything. And we always had this somewhat hot and boozy alcohol flavor and S-04 really mutes hop aroma rather than accentuating it. We tried every permutation of recipes and mashing and fermentation techniques over the years, and never really got it to work - at least in the way we wanted. I recognize S-04 quite easily now, and that is why I'm quite confident in saying that I doubt that Tree House is using S-04 as their base yeast. Having had a few of their beers, I didn't recognize the flavor as S-04 at all. However I'm also sure it's not something like London Ale III, but it's not far off.
We ended up having to assault the beers with dry-hopping to overcome this muting effect and it never really went our way. Only when we switched to LAIII derivatives and other English strains did we get more hop aroma and flavor.

Just thinking of the logistics, if Tree House was using a dry yeast blend, then they have to pitch fresh yeast every time, otherwise their blend would get out of balance after the first fermentation. That means maybe 5-10 kg of dry yeast pr. Tank (I forget their biggest tank size but I believe the GEA brewhouse is around 80 hL). That's a massive cost, something I really can't see them doing for every brand. Them doing it every now and then is possible, but for every IPA they make or even the majority? No way. The cost of yeast pr batch would be enormous.

However, it seems like that from other threads and articles that they do indeed use a mixed yeast culture for Julius, which seems reasonable, as it started life as a homebrew recipe from what I know.

Just throwing another thought out there; I know of at least 2 breweries that intentionally add different yeasts post fermentation, in order to screw up the blend so that people can't easily culture up their dregs and to keep their real yeast "secret". I'm not saying TH are doing that, it's just worth mentioning that it happens. Contamination in the brewery is also possible.

Anyway, just throwing some professional S-04 experience out there.

For a typical brewery I would agree that using fresh yeast every time probably isn’t cost efficient. For a brewery that probably averages $10,000+ of can sales an hour out their front door, I don’t think it’s an issue.

 

[TheHairyHop]

For a typical brewery I would agree that using fresh yeast every time probably isn’t cost efficient. For a brewery that probably averages $10,000+ of can sales an hour out their front door, I don’t think it’s an issue.

They started very very small. I don’t think this logic applies

 

[TBryerton]

They started very very small. I don’t think this logic applies

I don’t think this conversation has anything to do with how they started. The point being argued is that a company brewing a large quantity of beer can’t justify the cost of using new yeast for each batch. My argument is that their sales can justify it.

And to your point, yes they started very small, to the extent they weren’t much larger than some home brewers in terms of quantity. So as a home brewer, if you could make a much better beer by using fresh yeast each batch, wouldn’t you?? I would bet a high % of home brewers are not harvesting yeast.

 

[TheHairyHop]

I don’t think this conversation has anything to do with how they started. The point being argued is that a company brewing a large quantity of beer can’t justify the cost of using new yeast for each batch. My argument is that their sales can justify it.

And to your point, yes they started very small, to the extent they weren’t much larger than some home brewers in terms of quantity. So as a home brewer, if you could make a much better beer by using fresh yeast each batch, wouldn’t you?? I would bet a high % of home brewers are not harvesting yeast.

Small breweries have a very strong motivation to minimize cost. The more yeast you need to buy actually makes it ultimately cost less per unit sold, thereby impacting your profit less. The smaller your batch, and the less yeast required, actually ends up costing more per unit and affecting your bottom line more. Small Treehouse would have a larger motivation to repitch than large Treehouse.

 

[TBryerton]

Small breweries have a very strong motivation to minimize cost. The more yeast you need to buy actually makes it ultimately cost less per unit sold, thereby impacting your profit less. The smaller your batch, and the less yeast required, actually ends up costing more per unit and affecting your bottom line more. Small Treehouse would have a larger motivation to repitch than large Treehouse.

Considering their business model when they first started, I completely disagree. And the science throughout this entire thread backs me up. Tree House has even confirmed it’s a yeast blend, so I’m not sure why this is an argument.

 

[Clyde McCoy]

Been reading this thread ever since it came out, and it's really interesting. This theard made a bit of a stir in the industry when it started, at least for us interesseret in microbiology.

I am a professional brewer in Copenhagen, I used to work for a small craft brewery that is now a very large craft brewery. I just quit there to start my own brewery. And in that regard, I worked at a brewpub and we were producing some of the best rated IPA's in the country. For years we used S-04 as our house strain for almost everything. And we always had this somewhat hot and boozy alcohol flavor and S-04 really mutes hop aroma rather than accentuating it. We tried every permutation of recipes and mashing and fermentation techniques over the years, and never really got it to work - at least in the way we wanted. I recognize S-04 quite easily now, and that is why I'm quite confident in saying that I doubt that Tree House is using S-04 as their base yeast. Having had a few of their beers, I didn't recognize the flavor as S-04 at all. However I'm also sure it's not something like London Ale III, but it's not far off.
We ended up having to assault the beers with dry-hopping to overcome this muting effect and it never really went our way. Only when we switched to LAIII derivatives and other English strains did we get more hop aroma and flavor.

Just thinking of the logistics, if Tree House was using a dry yeast blend, then they have to pitch fresh yeast every time, otherwise their blend would get out of balance after the first fermentation. That means maybe 5-10 kg of dry yeast pr. Tank (I forget their biggest tank size but I believe the GEA brewhouse is around 80 hL). That's a massive cost, something I really can't see them doing for every brand. Them doing it every now and then is possible, but for every IPA they make or even the majority? No way. The cost of yeast pr batch would be enormous.

However, it seems like that from other threads and articles that they do indeed use a mixed yeast culture for Julius, which seems reasonable, as it started life as a homebrew recipe from what I know.

Just throwing another thought out there; I know of at least 2 breweries that intentionally add different yeasts post fermentation, in order to screw up the blend so that people can't easily culture up their dregs and to keep their real yeast "secret". I'm not saying TH are doing that, it's just worth mentioning that it happens. Contamination in the brewery is also possible.

Anyway, just throwing some professional S-04 experience out there.

How heavily were you dry hopping? Tree House has an IIPA (Live Free) that is "dry-hopped with over eight pounds per barrel." I'd bet their base IPAs start at 3-4 lbs/bbl and increase from there.

As for the strains, you really don't find these convincing?

 

[Northern_Brewer]

As for the strains, you really don't find these convincing?

Personally I think it's quite plausible that in the early days as a small brewery they effectively outsourced yeast management/QC to Fermentis, but then building the new facility allowed them the lab facilities to bring it in-house with potentially a different strain. There's plenty of other breweries that have followed a similar path.

 

[Mousetrapbrewery]

I just made an Irish Stout with S-04 and the smell and taste reminds me of walking into the treehouse and getting the smell of yeast. I’m very confident they use S-04, it’s just how they use it and with what else. I remember reading that someone made a starter with either T-58 or WB-06 and the smell was bubblegum. Has anyone tried to underpitch S-04 and use starters for the other two later in the fermentation?

 

[Dextersmom]

Have you tested an Equilibrium beer yet? I’m curious to see what that shows. I get that over ripe banana ester in some of their beers.

I'd love to examine their beer to get an idea of how they finagle their "juice treatment" into the beers.... I was and still may be convinced it's a flavoring or terpene of some sort. It's so distinctly "flavored" whereas TH comes across as more of a yeast / Ester biproduct.

 

[beervoid]

I'd love to examine their beer to get an idea of how they finagle their "juice treatment" into the beers.... I was and still may be convinced it's a flavoring or terpene of some sort. It's so distinctly "flavored" whereas TH comes across as more of a yeast / Ester biproduct.

If they use terpenes wouldnt they have to put it on the ingredient list on the label?

 

[Dextersmom]

Also been thinking while driving for the last 12hrs...i had their black ipa at one point and caught some of the bubblegum / melon on that guy and remembered thinking it was a turn-off because that shouldn't really be a component of a black ipa. So taking that into account... Would all of the yeast blending / krausening etc ideas still hold up? I think it's doubtful they'd include a major complex process to produce a specific Ester profile for a beer it's not suited for.... Could this all be explained by their use of a proprietary yeast strain that shows similar traits which is why when it's tested in the lab we see S04, wb06, and t58? Pardon my lack of science when it comes lab analysis.... Just me speculating which I'm sure has already been discussed and suggested in previous postings...

@beervoid if EQ is using a terpene or flavoring I don't think they'd need to list it. Plenty of breweries not listing all of their ingredients. Especially if the incidence of reported allergic sensitivity is insignificant. I mean C'mon 450 north got away with printing wildly different abv levels on their beers and only caught flack from beer nerds.

 

[beervoid]

Also been thinking while driving for the last 12hrs...i had their black ipa at one point and caught some of the bubblegum / melon on that guy and remembered thinking it was a turn-off because that shouldn't really be a component of a black ipa. So taking that into account... Would all of the yeast blending / krausening etc ideas still hold up? I think it's doubtful they'd include a major complex process to produce a specific Ester profile for a beer it's not suited for.... Could this all be explained by their use of a proprietary yeast strain that shows similar traits which is why when it's tested in the lab we see S04, wb06, and t58? Pardon my lack of science when it comes lab analysis.... Just me speculating which I'm sure has already been discussed and suggested in previous postings...

@beervoid if EQ is using a terpene or flavoring I don't think they'd need to list it. Plenty of breweries not listing all of their ingredients. Especially if the incidence of reported allergic sensitivity is insignificant. I mean C'mon 450 north got away with printing wildly different abv levels on their beers and only caught flack from beer nerds.

Their Bright series don't have have the typical yeast esters? They probably wanted that black ipa to have their signature flavor.

Since terpenes are a part of hops it might be possible they dont need to list it but it would be nice to have some clarity on that, I have no clue on the laws.

 

[beervoid]

Reading through yeast science, its clear that gravity has a high correlation with ester formation. The higher the gravity the more ester production.
What if you brew a very high gravity beer to maximize esters then blend that back into the main beer.

 

[beervoid]

Also, what if you raise the PH after KO to stress the yeast, has anyone here tried that?

 

[Mousetrapbrewery]

Also, what if you raise the PH after KO to stress the yeast, has anyone here tried that?

Those are interesting points. I know someone originally suggested they mix beers. But I don’t think anyone actually tried it.

 

[TBryerton]

Those are interesting points. I know someone originally suggested they mix beers. But I don’t think anyone actually tried it.

I’ve tried mixing beers. Didn’t taste like TH. I’m curious about using PH as well, it’s an interesting thought. I’m assuming our DNA experts on here are correct, but it’s interesting that the esters in a TH core beer don’t come close to resembling the esters from the three yeasts in question, at least in my experience. I’ve played with wb06 quite a bit now, and at this point it’s pretty simple for me to pick out that yeast. Even at extremely low % (direct pitch at beginning of fermentation) it’s very obvious. I’m going to switch and spend more time experimenting with t58, because I can’t get wb06 to taste anything like TH, but I’m going to guess I’ll end up at the same crossroads. Which has me asking, WTF are they doing to get that flavor?

The other thing that stands out to me, is that they have gotten good at controlling the amount of esters. For example, Queen J, which I would assume is DH’d at the same rate as KJ, was borderline overwhelming in terms of that core TH flavor. My first thought was that they used some type of purée, then after a few more sips I realized it was the yeast. So I think it’s important to keep in mind that (1) they have a way of controlling amount of specific esters, (2) they can produce an overwhelming amount of esters, and (3) the esters they’re producing don’t seem to be the normal esters for the yeast being used.

That being said, I’m just a dude brewing beer in his garage making random observations and in no way a yeast specialist. Point being, the scientists and actual brewery owners on here are probably much more knowledgeable about this stuff.

 

[NJGeorge]

I’ve tried mixing beers. Didn’t taste like TH. I’m curious about using PH as well, it’s an interesting thought. I’m assuming our DNA experts on here are correct, but it’s interesting that the esters in a TH core beer don’t come close to resembling the esters from the three yeasts in question, at least in my experience. I’ve played with wb06 quite a bit now, and at this point it’s pretty simple for me to pick out that yeast. Even at extremely low % (direct pitch at beginning of fermentation) it’s very obvious. I’m going to switch and spend more time experimenting with t58, because I can’t get wb06 to taste anything like TH, but I’m going to guess I’ll end up at the same crossroads. Which has me asking, WTF are they doing to get that flavor?

The other thing that stands out to me, is that they have gotten good at controlling the amount of esters. For example, Queen J, which I would assume is DH’d at the same rate as KJ, was borderline overwhelming in terms of that core TH flavor. My first thought was that they used some type of purée, then after a few more sips I realized it was the yeast. So I think it’s important to keep in mind that (1) they have a way of controlling amount of specific esters, (2) they can produce an overwhelming amount of esters, and (3) the esters they’re producing don’t seem to be the normal esters for the yeast being used.

That being said, I’m just a dude brewing beer in his garage making random observations and in no way a yeast specialist. Point being, the scientists and actual brewery owners on here are probably much more knowledgeable about this stuff.

Agreed, or they might be even using a entirely different yeast all together and not the ones were using. I haven't brewed in a while but Ill give it a shot soon and play around more with different yeast. I wonder if they are even naturally carbonating anymore with the amount of beer they are pumping out. I'm sure there were process changes along the way. So many people bashing treehouse these days its crazy. I've noticed a dip in quality as well. To me, only the double IPA's have that strong yeast ester going on.

 

[beervoid]

Agreed, or they might be even using a entirely different yeast all together and not the ones were using. I haven't brewed in a while but Ill give it a shot soon and play around more with different yeast. I wonder if they are even naturally carbonating anymore with the amount of beer they are pumping out. I'm sure there were process changes along the way. So many people bashing treehouse these days its crazy. I've noticed a dip in quality as well. To me, only the double IPA's have that strong yeast ester going on.

I think this is key, the double ipa's have those esters going on. Og is directly related to ester formation.
Apart from maybe not using the right yeast perhaps we should focus more on pushing any particular yeast to maximize esters.
Start with a high og. Low aeration. The right nutrition.
I've gotten some valine and l-leucine to play with on batches.

 

[NJGeorge]

I think this is key, the double ipa's have those esters going on. Og is directly related to ester formation.
Apart from maybe not using the right yeast perhaps we should focus more on pushing any particular yeast to maximize esters.
Start with a high og. Low aeration. The right nutrition.
I've gotten some valine and l-leucine to play with on batches.

I've got valine and l-leucine as well and mentioned them way earlier in this thread. Only tried some on one batch but didn't have the best control then and there were fusels. There is no literature out there on how to use the stuff though. Any thoughts on amounts? Worth a shot to play around with.

 

[TBryerton]

Agreed, or they might be even using a entirely different yeast all together and not the ones were using. I haven't brewed in a while but Ill give it a shot soon and play around more with different yeast. I wonder if they are even naturally carbonating anymore with the amount of beer they are pumping out. I'm sure there were process changes along the way. So many people bashing treehouse these days its crazy. I've noticed a dip in quality as well. To me, only the double IPA's have that strong yeast ester going on.

I find the majority of breweries making this style to be inconsistent, but yes, TH is probably at the top of that list. The thing for me is that when they nail a batch, it’s usually something pretty spectacular. I’m not finding that many other places. I’d rather drink my own stuff than the majority of popular IPA factories these days. It seems like once a month I hear about some brewery that makes better beer than TH, then I go out of may to get it and it’s mediocre at best. In October I made a run up to Portland, ME and all the beer I brought back was pretty impressive (if you haven’t had Belleflower I would add that to your list) but then I cracked a Gggreennn and was a level above everything. Probably the best beer I’ve had in 2021. Those esters and the Galaxy hops go together like peanut butter and jelly. But yes, I’ve had mediocre cans of Green too. And if I remember correctly that was a beer (green or VG) that came back with a lot of T58 samples.

 

[beervoid]

I've got valine and l-leucine as well and mentioned them way earlier in this thread. Only tried some on one batch but didn't have the best control then and there were fusels. There is no literature out there on how to use the stuff though. Any thoughts on amounts? Worth a shot to play around with.

Here is a quote from some research:

"
A broad range of aroma-active esters produced during fermentation are vital for the complex flavour of beer. This study assessed the influence of fermentation temperature, pH, and wort nutritional supplements on the production of yeast-derived ester compounds and the overall fermentation performance. The best fermentation performance was achieved when wort was supplemented with 0.75 g/l l-leucine resulting in highest reducing sugar and FAN (free amino nitrogen) utilization and ethanol production. At optimum fermentation pH of 5, 38.27% reducing sugars and 35.28% FAN was utilized resulting in 4.07% (v/v) ethanol. Wort supplemented with zinc sulphate (0.12 g/l) resulted in 5.01% ethanol (v/v) production and 54.32% reducing sugar utilization. Increase in fermentation temperature from 18°C to room temperature (±22.5°C) resulted in 17.03% increased ethanol production and 14.42% and 62.82% increase in total acetate ester concentration and total ethyl ester concentration, respectively. Supplementation of worth with 0.12 g/l ZnSO4 resulted in 2.46-fold increase in both isoamyl acetate and ethyl decanoate concentration, while a 7.05-fold and 1.96-fold increase in the concentration of isoamyl acetate and ethyl decanoate, respectively was obtained upon 0.75 g/l l-leucine supplementation. Wort supplemented with l-leucine (0.75 g/l) yielded the highest beer foam head stability with a rating of 2.67, while highest yeast viability was achieved when wort was supplemented with 0.12 g/l zinc sulphate. Results from this study suggest that supplementing wort with essential nutrients required for yeast growth and optimizing the fermentation conditions could be an effective way of improving fermentation performance and controlling aroma-active esters in beer."

https://www.sciencedirect.com/science/article/abs/pii/S1389172313002211?via=ihub

 

[echoALEia]

Hope everyone is well! Two questions:

1. Is there anyone doing PCRs on yeasts currently?
2. Does anyone know around when Julius changed from the clearer/deep orange version to the hazy version it became today?

Thanks and Cheers!

 

[NJGeorge]

Hope everyone is well! Two questions:

1. Is there anyone doing PCRs on yeasts currently?
2. Does anyone know around when Julius changed from the clearer/deep orange version to the hazy version it became today?

Thanks and Cheers!

It was clearer in 2013-2014 and went a little more hazy in 2015. Check out their Instagram.

 

[beervoid]

It was clearer in 2013-2014 and went a little more hazy in 2015. Check out their Instagram.

I would bet it's due to dryhopping rates.

 

[TBryerton]

I would bet it's due to dryhopping rates.

Im sure they’ve upped their DH amounts, but my $ would be on grain bill. I’m still convinced their core beers are dry hopped at a low rate compared to todays standards. The difference in Julius and JJJ is to the point you would think they’re completely different beers.

 

[NJGeorge]

I would bet it's due to dryhopping rates.

Could be anything honestly. Were guessing. Could be different grain, hops, yeast. Who knows.. Unless Nate or an employee says something, we'll never know. Supposedly they used a little Munich in Julius back in the day. Could be something different today. Same thing with the yeast. Nate supposedly used S05 back in the day too. Seems like everyone in this thread has lost interest. What ever happened to that analysis done on a can of Julius in the UK? They mentioned one of the yeast was definitely Belgian but i have heard anything since.

 

[JJ900]

Here is a quote from some research:

"
A broad range of aroma-active esters produced during fermentation are vital for the complex flavour of beer. This study assessed the influence of fermentation temperature, pH, and wort nutritional supplements on the production of yeast-derived ester compounds and the overall fermentation performance. The best fermentation performance was achieved when wort was supplemented with 0.75 g/l l-leucine resulting in highest reducing sugar and FAN (free amino nitrogen) utilization and ethanol production. At optimum fermentation pH of 5, 38.27% reducing sugars and 35.28% FAN was utilized resulting in 4.07% (v/v) ethanol. Wort supplemented with zinc sulphate (0.12 g/l) resulted in 5.01% ethanol (v/v) production and 54.32% reducing sugar utilization. Increase in fermentation temperature from 18°C to room temperature (±22.5°C) resulted in 17.03% increased ethanol production and 14.42% and 62.82% increase in total acetate ester concentration and total ethyl ester concentration, respectively. Supplementation of worth with 0.12 g/l ZnSO4 resulted in 2.46-fold increase in both isoamyl acetate and ethyl decanoate concentration, while a 7.05-fold and 1.96-fold increase in the concentration of isoamyl acetate and ethyl decanoate, respectively was obtained upon 0.75 g/l l-leucine supplementation. Wort supplemented with l-leucine (0.75 g/l) yielded the highest beer foam head stability with a rating of 2.67, while highest yeast viability was achieved when wort was supplemented with 0.12 g/l zinc sulphate. Results from this study suggest that supplementing wort with essential nutrients required for yeast growth and optimizing the fermentation conditions could be an effective way of improving fermentation performance and controlling aroma-active esters in beer."

https://www.sciencedirect.com/science/article/abs/pii/S1389172313002211?via=ihub

This is a nice quote. Did the research specify over what time the rise from 18C to room temp was? free-rise or controlled etc?

I also noted the "highest beer foam head stability" and TH beers certainly have an impressive head and those tiny bubbles.